I have lockers next to the mailbox and I'm in the US. They just put a key to the locker in your box and then you go unlock the locker and the key is 'caught' and won't re-close. Yeah, it's not a perfect system, but it doesn't go out when the power goes down and it isn't going to get taken over by Bratslavian hackers to try to sell my neighbors Viagra via Twitter and even the most tech-illiterate/disabled people can use it fine.